Galaxias mungadhan, Raadik, 2014

Raadik, Tarmo A., 2014, Fifteen from one: a revision of the Galaxias olidus Günther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognises three previously described taxa and describes 12 new species, Zootaxa 3898 (1), pp. 1-198 : 86-91

Galaxias mungadhan , new species

Dargo Galaxias

( Tables 4 to 9, 12, 27 & 28; Figures 7 & 20 )

Galaxias olidus olidus Günther, 1866 — Frankenberg, 1969: 170 (partim).

Galaxias olidus (non G. olidus Günther, 1866 )— Dixon, 1976: 111; McDowall & Frankenberg, 1981: 469 (partim); Cadwallader & Backhouse, 1983: 69 (partim); McDowall, 2003a: 364 (partim).

Galaxias findlayi (non G. findlayi Macleay, 1882 )— Dixon, 1976: 111.

Galaxias sp. 6 — Raadik & Nicol, 2012; 1; DSE, 2013: 17; Raadik & Nicol, 2013:1.

Galaxias sp. 16— Kuiter, 2013; 76.

Conforms to the allozymically defined and morphologically diagnosed taxon ‘DA’ of Adams et al. (2014), and ‘dargo’ of Raadik (2011).

Material Examined.

Holotype. NMV A.30550- 3, 104.5 mm LCF, (94.2 mm SL), female, Lightbound Creek, on Dargo High Plains Road, Lankey's Plain , Dargo High Plains , Alpine National Park , Victoria, 37° 06' 33”S 147° 09' 40”E, T.A. Raadik, 20 March 2002.

Paratypes. AMS I.44913-1 (2), and NMV A.30550-2 (8), 64.2–90.9 mm LCF (56.8–80.9 mm SL), collected with holotype; NMV A.30588-1 (10), 62.3–88.6 mm LCF (55.0– 78.1 mm SL), Lightbound Creek , at type locality, R.H. Parrish, 10 December 1963 .

Non-type material. NMV A.30550-1 (7), collected with holotype; NMV A.12682 (23), Lightbound Creek, collected with NMV A.30588-1; NMV A.12405 (5), Lightbound Creek, at type locality, 9 May 1962; NMV A.12674 (57), Lightbound Creek, at type locality, 10 December 1963; NMV A.486 (4), Lightbound Creek, at type locality, 9 November 1974; NMV A.488 (1), Lightbound Creek, at type locality, 10 November 1974; NMV A.487 (7), Lightbound Creek, at type locality, 11 November 1974; NMV A.26402-1 (5), Lightbound Creek, at type locality, 16 April 2008.

Diagnosis. Galaxias mungadhan sp. nov. differs from all other species within the Galaxias olidus complex by a combination of the following characters: distance between pelvic and anal fin bases long (22.4–27.7 % SL); head shallow (30.0–42.6 % HL) and post-orbital head length long (54.7–62.4 % HL); inter-orbital narrow (35.1–40.4 % HL); nostrils of moderate length, not visible from ventral view; dorsal and anal fin origins set far back along trunk (70.5–74.5 and 74.4–79.9 % SL, respectively); body depth through pectoral fin base greater (121.2 % SL) than that through vent; anal fin base short (9.0–10.7 % SL), usually shorter than dorsal fin base; dorsal fin short (13–15 % SL) and anal fin moderately short (13.2–15.6 % SL); lower jaw length much shorter (67.8–89.0 %) than width of gape; expanded rays of caudal fin equal to or less than body depth through pectoral fin base; dorsal midline usually flattened anteriorly from above or slightly posterior to pectoral fin bases; usually 10 segmented anal fin rays; posterior extent of mouth about 0.8 ED below ventral margin of eye; pyloric caecae either present or absent, if present, as a single, wide and blunt, short (0.7 % SL) caecum; gill rakers short and stout; anal fin origin usually under 0.61 distance posteriorly along dorsal fin base; lack of distinct black bars along lateral line; and, usually a dark chocolate brown overall when alive.

Description. As for the genus and members of the Galaxias olidus complex, except as indicated below, based on 21 specimens, 55.0– 94.2 mm SL, and 18 additional, non-type, specimens for meristics. See Tables 4 to 9 for frequencies of meristic values and Table 27 for a summary of meristic variation. Segmented dorsal fin rays 10 (9–11), of these 8 (7–9*) branched and 2 (1*–2) unbranched; segmented anal fin rays 10 (10–11), of these 8 (8–9) branched and 2 unbranched; caudal fin rays 16 (15–16); segmented pectoral fin rays 15 (14–15), of these 13 (12–13) branched and 2 unbranched; pelvic fin rays 7 (7–8*), of these 6 (6–*7) branched and one unbranched; gill raker total count (lower limb and upper limb) 12 (11–13*), lower arch with 9 (8–9) and 3 (3–4*) on upper, variation on first gill arch 8+3 (4), 8+4 (1), 9+3 (10), 9+4 (8*), 10+3 (2); vertebrae 52 (52–55); 0–1* pyloric caecae on stomach.

See Table 28 for comparative value ranges of morphometric characters. Body moderately deep and long, dorsal midline usually flattened anteriorly from above or slightly posterior to pectoral fin bases, depth through pectoral base 1.2 (1.1–1.3) that through vent, trunk with dorsal profile relatively flattish and somewhat depressed on head and ventral profile evenly arched from snout to anal fin; body tapering back to a caudal peduncle of moderate length, 8.0 (7.2–9.4 in SL), and depth, 12.8 (11.7–13.5), the peduncle depth 1.6 (1.3–1.8) in its length; accessory lateral line present. Head of moderate length (4.2–4.7 in SL) and 1.1–1.2 in PelAn distance, relatively shallow, 2.7 (2.3–3.3) in HL, moderately wide, 1.6 (1.5–1.8) in HL, distinctly wider than deep (depth about 1.7 in HW), lateral profile obtuse with dorsal profile distinctly flat anterior to nape; eyes of moderate size, 5.5 (5.0–6.1) in HL and 2.0 (1.6–2.5) in HD, situated high on head, just below dorsal head profile, interorbital flat and relatively narrow, 2.7 (2.5–2.8) in HL and 2.0 (1.9–2.3) times ED; cheeks expanded below eyes, eye profiles usually not visible laterally from ventral view; snout shortish, 3.6 (3.4–4.0) in HL and 1.5 (1.2–1.8) times ED, lateral profile rounded, profile from above and below evenly rounded without obvious inflections; post-orbital head length long, 1.7 in HL; nostrils of moderate length, just extending to posterior edge of upper lip, not visible from ventral view; mouth usually terminal or very slightly subterminal, of moderate length, 2.8 (2.6–3.1) in HL, posterior extent reaching back to under anterior 0.3 of eyes, and about 0.7 (0.6–1.0) ED below ventral margin of eye, most anterior tip of upper lip level with about middle of eye, gape moderately wide, 2.5 (2.3–3.1) in HL, width 1.1 times length of upper jaw and 1.6 (1.4–1.8) in HW. Jaws subequal, lower 1.1 in length of upper, upper jaw relatively thick and fleshy. Pyloric caecum, if present, short, averaging 0.7 % SL (0.1–1.6 %), wide and bluntly rounded; gill rakers short, stout and rounded to bluntly pointed.

Fins fleshy at bases, median fins more so, with thickening extending distally over 0.3–0.5 of fin area, extending farther between fin rays; dorsal and anal fin bases of moderate length and usually equally long, fins short and rounded, of equal length or dorsal very slightly shorter, middle rays longest; anal fin origin usually under 0.62 (0.41–0.96) distance posteriorly along dorsal fin base. Pelvic fins of moderate length, 9.1 (8.2–9.8) in SL, 1.2 (1.1–1.4) in pectoral fin length, inserted at about mid-point of standard length and usually extending to 0.4 distance to anal fin base; pectoral fin longish and paddle-shaped, 7.5 (6.7–8.3) in SL, usually extending 0.45 distance to pelvic fin base, low on body with dorsal end of fin base level with posterior extent of mouth, lamina of paired fins oriented anterio-ventrally to ventrally, raised lamellae on ventral surface of rays usually present and moderately to strongly developed. Caudal fin of moderately length, 7.6 (6.7–8.3) in SL, emarginate, usually 1.1 times length of caudal peduncle, vertical width of expanded rays equal to or less than body depth through pectoral fin base, flanges low and well developed along caudal peduncle and long, reaching anteriorly past distal end of adpressed anal fin rays to near fin base.

Size. Recorded to 110 mm LCF and 11 g; commonly to 70–80 mm LCF.

Colour in life. Body dark brown overall, usually darker above lateral line, extending onto top and sides of head and snout, becoming brown ventrally, belly sometimes light brown. Overlain by small to moderate sized dark brown to black, irregular shaped, rather diffuse blotches, more densely spaced above lateral line. Gill cover brown; iris silvery to coppery gold. Mid-dorsal surface of trunk usually with a moderately wide band composed of gold spots or flecks extending from nape to dorsal fin base, sometimes extending over head to snout; head broadly scattered with small gold flecks, and broad, diffuse band of golden spots usually extending from near base of pectoral fin onto caudal peduncle, usually mostly below lateral line and quite distinct posteriorly. Fins translucent yellowy brown. See below for more detailed comments on body pattern.

Colour of preserved material. Base colour of head and body tan to light brown. Fine to medium-size, irregularly shaped, diffuse brown, dark grey to black blotches densely spaced on dorsal surface of trunk, extending down sides to lateral line, also extending onto top of head. Prominent trunk patterning ends abruptly at lateral line, continuing below but extremely pale, conferring a two-tone pattern, darker on top. Trunk patterning overlain by light shading of fine brown stippling, distinctly darker above lateral line and fading ventrally, merging well below lateral line with faint trunk pattern. Dorsal trunk pattern extends over dorsal surface of head to snout and upper lip, though pale, also extending laterally onto cheeks and behind eye.

Eye grey to black, pupil translucent pale orange-yellow. Teeth translucent yellow to pale orange–yellow, tips orange to orange–red; gill rakers cream to pale yellow. Fins pale creamy yellow, becoming more translucent on posterior margins, fleshy bases of dorsal, anal, pelvic and pectoral fins with fine brown stippling, trunk pattern just extending onto base of caudal fin. Fin rays opaque, external edges of rays highlighted with fine brown spots forming thin lines, first few rays generally darker.

Etymology. The specific name mungadhan, from ‘munga’ meaning from, and ‘dhan’ meaning frost or snow, in reference to its distribution at high elevations on the Dargo High Plains which are usually covered by snow during winter. From the language of the Gunai/Kurnai indigenous nation, the traditional inhabitants of the Gippsland region of Victoria ( Gardner 1996). Suggested vernacular name as the ‘Dargo Galaxias’.

Genetics. Allozyme and mtDNA analysis of this species can be found in Adams et al. (2014; taxon code DA). Diagnostic allozyme loci (6–12) between this taxon and the other species in the Galaxias olidus complex are provided in Table 12.

Distribution. See Fig. 7 . Only known from a short section of creek extending from 700 m downstream of the type locality to the top of the catchment, in the headwaters of Lightbound Creek, a tributary of the Dargo River, Mitchell River system in the coastal Gippsland region of Victoria, from an elevation of 1550 m asl. The population is known to extend over approximately 2 km (river distance) from the source, which is at 1620 m asl, in a catchment of approximately 4 km 2. Downstream distribution unknown, though waterfalls are present 2 km farther downstream at Devils Hollow, which are located 2 km upstream from the junction with the Dargo River. Alien trout are abundant throughout the Dargo River system, and possibly within the lower Lightbound Creek upstream to the falls, possibly restricting the distribution of Galaxias mungadhan to a 4 km length of creek in a catchment of 9 km 2. Historical distribution unknown, though suspected, based on anecdotal records, to have been more widespread, possibly throughout the majority of the upper Dargo River system before trout reduced their range.

Sympatry. Only species of Galaxias found within its current restricted range, though considered to have been historically found with Galaxias olidus , which is present nearby. Alien trout have substantially altered distributional patterns in the last 150 years and fragmented and reduced the distributional range of galaxiids and their populations. Galaxias brevipinnis , Galaxias maculatus and Galaxias truttaceus are found farther downstream in the Dargo River system and their ranges may also have historically overlapped with that of Galaxias mungadhan .

Habitat. Recorded from a small (0.5–1.3 m average width and 0.05–0.40 m in average depth), cool, clear, alpine creek, flowing through a grassy plain, consisting predominantly of riffles and pools, and with very little shading except that provided by grasses. During winter the catchment is often covered by snow for varying periods of time. Substrate consisted predominantly of bedrock with some loose boulders, with smaller amounts of pebble, gravel, sand and clay, overlain in backwaters by silt. Instream cover was provided by rock and by bank and vegetation (alpine grasses) overhang, and pools averaged 0.5 m in depth.

General Biology. Confined to freshwater and considered not to undertake diadromous migrations. Recorded at densities of 4.2–6.4 fish/m 2 and is the only native fish species so far recorded from within its range. Spawning period unknown and possibly annually variable depending on conditions. Adult fish sampled in mid-November (2010) and mid-December (1963) were full of fat deposits and their gonads were in an early stage of development, whereas those collected in mid-April (2008) were at an advanced stage of development, with many females ripe to nearly ripe and with large eggs which were beginning to separate. The smallest presumed 0+ age fish recorded in mid-November (1974) was 27 mm LCF, and 38 mm LCF in mid-December 1963, with approximately 30 % of fish collected in late March (2002) less than 50 mm LCF (smallest 27 mm LCF) and in mid-April (2008) 75 % of 100 fish collected less than 40 mm LCF, with 94 % <50 mm LCF, all considered of 0+ age. This suggests an extended spawning period possibly from late winter to spring, though a 0+ age fish of 18.1 mm LCF, still possessing a midventral larval keel, was collected in early May (1962), suggesting a late March to April (autumn) spawning. Able to survive in very cold water (<5 o C) during winter.

Conservation status. Critically endangered ( DSE 2013).

Remarks. Pyloric caecae are usually absent and the anterior portion of the intestine is usually relatively evenly swollen around its circumference, and much wider in diameter than the posterior end of the stomach. Occasionally, a rudimentary caecum were considered present if there was a small but distinctive distension to this swelling, usually at right angles.

A dark galaxiid was observed (but not caught) amongst trout in the very upper reaches of the Dargo River system, off the very northern section of the Dargo High Plains Road, in 1963, and ‘minnows’ (= Galaxias sp. ) were reported to be present in 1961 above a set of falls (with trout below) in the upper reaches of a tributary flowing between Mt. Blowhard and Little Mount Baldy, though they were not recorded in March 1963 (R. Frankenberg, pers. comm. 2011). Recent surveys in nearby tributaries to Lightbound Creek (Twenty Five Mile Creek, Thirty Mile Creek, Little Dargo River, and small eastern tributaries of the Dargo River) have failed to record Galaxias mungadhan , at additional locations, though Galaxias olidus were located in some catchments ( Raadik & Nicol 2012).

Systematic survey effort, focussing on headwater sections of smaller streams in the upper reaches of the Dargo River system, and the headwater reaches of the adjacent Wonnangatta and Wongungarra river systems, is required to determine if additional, remnant populations of Galaxias mungadhan remain, to accurately delineate the distribution of this species, to search for suitable potential translocation sites within its presumed former range, and to determine if other potentially novel species in the Galaxias olidus complex are present.

Figures

FIGURE 7. Distribution of Galaxias aequipinnis (open circles), Galaxias brevissimus (grey square), Galaxias gunaikurnai (black square), Galaxias lanceolatus (grey circle), Galaxias longifundus (black diamond), Galaxias mcdowalli (inverted black triangle), Galaxias mungadhan (open squares), Galaxias supremus (open triangle), Galaxias tantangara (grey triangle), and Galaxias terenasus (black circles) (river basins shown—refer to Fig. 1).

FIGURE 20. A–B: Galaxias mungadhan sp. nov. holotype, NMV A.30550-3, 104.5 mm LCF, Lightbound Creek, Dargo High Plains Road, Lankey's Plain, Alpine National Park, Victoria, A) line drawing (R. Plant), B) image of preserved specimen (T.A. Raadik); G. mungadhan sp. nov., collected from the type locality, 5 April 2011; ~ 90 mm LCF. (T.A. Raadik); D) Lightbound Creek, at type locality of G. mungadhan sp. nov., 16 November 2010 (T.A. Raadik). Scale bar = 5 mm.